An agreeable series of animal sketches, but disappointingly general for anyone seeking information on the aging process and the status of current research. After the first chapter which introduces cell division, glands and hormones, and the concept of a ""biological time clock,"" Hopf does not get back to these matters until the last few pages where she cites the conflicting view of two researchers. Meanwhile a scattered variety of animals is surveyed, and though Hopf does include lifespan data for each and frequently alludes to longevity/size relationships, she allots more attention to such loosely (if at all) related matters as toads' camouflage, tortoise protection laws, parrots' nest building, elephants' trunks, and gorilla sociability. Her single chapter on plants (chiefly the giant trees) mentions that tannic acid in the sap ""may be one answer"" to the redwoods' and sequoias' long lives; and the chapter on humans concentrates on three long-lived societies (located in Ecuador, the Caucasus, and the Himalayas). Otherwise this consists largely of readable animal profiles--for those with a general interest and not much specific background.